1. Field of the Invention
The present invention relates to a linear guide apparatus using a combination of balls and rollers as rolling members which are interposed between a guide rail and a slider travelling on the guide rail.
2. Description of the Prior Art
A prior art linear guide apparatus of this type is disclosed, for example, in Japanese Utility Model Laid-Open Publication No. 61-158324.
In this linear guide apparatus, as shown in FIG. 13, a multiplicity of balls 3 and rollers 4 are interposed as rolling members between a guide rail 1 and a slider 2 which is mounted straddling the guide rail 1. The balls 3 move while rolling within ball rolling grooves 5 opposing to each other formed in both side surfaces of the guide rail 1 and formed in both inner surfaces of the slider 2 as the slider 2 travels, and the balls 3 infinitely circulate through circulating paths 6. The rollers 4 move while rolling between an upper surface 1a of the guide rail 1 and an opposing inner surface 2a of the slider 2 and circulate infinitely through a circulating path 7.
In this manner, by using not only the balls but the roller train exhibiting high rigidity as the rolling members of the linear guide apparatus, the linear guide apparatus is allowed to provide a high load bearing capacity.
However, in the prior art linear guide apparatus using a combination of balls and rollers, since it is structured that the rollers 4 move while rolling on the upper surface 1a of the guide rail 1, the following drawbacks are involved.
(1) When the load which is loaded on the slider 2 is not a vertical load, since the rollers 4 can support only a vertical load, the balls 3 which are disposed in the lateral sides are loaded with undue load, and the load bearing capacity is reduced.
(2) When the slider 2 is removed from the guide rail 1, the rollers 4 will fall off the slider 2.
(3) Since a bolt hole 9 for fixing the guide rail 1 is bored in the guide rail 1, a uniform raceway can not be formed without securing a receway track 11 on the upper surface. However, it is impossible to secure the raceway track 11 on the upper surface of the guide rail 1 until the guide rail 1 has been fixed.